Centrifugal roller mill



June 2, .1970 I N.-H. soc-us 3,

CENTRIFUGAL ROLLER MILL I Filed June 16, 1967 I a sheets-sheet 1 INVENTORZ N62 so/v 29f Bows June 2, 1970 N. H. 50 3,515,356

OEN'I'RIFUGAL .ROL'LER MILL Filed June 16, 1967 2 Sheets-Sheet 2 INVENTOR.

NE! son) 75! 30 15 United States Patent O 3,515,356 CENTRIFUGAL ROLLER MILL Nelson H. Bogie, Gilbertsville, Ky. 42044 Filed June 16, 1967, Ser. No. 646,660 Int. Cl. B02c /08, 4/26 US. Cl. 24190 3 Claims ABSTRACT OF THE DISCLOSURE BACKGROUND OF THE INVENTION This invention relates to a centrifugal roller mill.

Although centrifugal roller mills are known in the art, nevertheless the material to be comminuted is generally fed axially through the mill chamber, and the centrifugally urged rollers engage a solid or smooth-surfaced cylindrical wall for crushing or pulverizing the material.

SUMMARY OF THE INVENTION It is therefore an object of this invention to provide a centrifugal roller mill in which the centrifugally urged crusher rollers are rotated about a horizontal axis within a horizontally disposed cylindrical crushing chamber. The crushing chamber comprises a cylindrical grate having a plurality of elongated slots of uniform and prede-l termined widths and disposed at acute angles to any radial plane of the cylindrical chamber. Both the acute angle of the slots and the widths of the slots determine the size of the comminuted material.

Another object of this invention is to provide a centrifugal roller mill in which the material to be comminuted is fed directly through the top portion of the horizontally disposed, slotted crushing chamber, and the comminuted material is discharged directly through the bottom of the chamber.

Another object of this invention is to provide a more efficient centrifugal roller crusher in which the crushing action and the sizing of the comminuted material is accurately controlled for more efficiency.

A further object of this invention is to provide a centrifugal roller mill having a cylindrical grate in which practically the entire grate wall is slotted for discharge of comminuted material from any portion of the grate wall.

Another object of this invention is to provide a centrif ugal roller mill having a grate including a plurality of angularly disposed elongated slots for more effective crushing action between the centrifugal rollers and the grate.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a central sectional elevational view of the invention mounted above a discharge conveyor mechanism, with the upper left quarter-section of the roller carrier and one roller disclosed in full end elevation;

FIG. 2 is a section taken along the line 2-2 of FIG.1; with portions broken away; and

FIG. 3 is a section taken along the line 3-3 of FIG. 1.

DESCRIPTION OF THE PREFERRED EMBODIMENT Referring now to the drawings in more detail, FIG. 1

discloses the centrifugal roller mill. made in accordance with this invention, including a housing 10 mounted upon a frame 11, and having an open bottom 12 for discharge of the comminuted material upon. a conveyor belt 13 for removing the comminuted material.

Mounted within the housing 10 upon supporting flanges 14 is a cylindrical grate 15 with its cylindrical axis disposed horizontally. The grate 15 includes a plurality of elongated slots 16 and forms a crushing chamber 17. These elongated slots 16 are preferably of uniform length and width, 'and each is preferably disposed at a uniform acute angle with any radial plane of the cylindrical grate 15 intersecting the particular slot 16. The slots 16 are preferably disposed in a herringbone pattern, two such patterns being disclosed in FIG. 2. Also as disclosed in four axially spaced series or sets, the slots in each set being substantially parallel to each other and circumferentially spaced through substantially the entire periphery of the grate 15, as disclosed in FIG. 1. Thus, practically the entire cylindrical grate 15 is slotted so that any material within the crushing chamber 17, when reduced to the size of the width of any slot 16, may be discharged from the chamber 17 to the space between the housing 10 and the grate 15 at practically any circumferential position within the chamber 17.

Mounted in the top portion of the grate 15 is a feed opening 18 supporting an upright feed chute 19, projecting through and above the top wall of the housing 10. The feed chute 19 is adapted to receive material to be comminuted, which drops by gravity into the crushing chamber 17.

Rotatably mounted within bearings 21 in the side Walls of the housing 10 is a carrier shaft 22, disposed coaxially of the cylindrical grate 15. The shaft 22 supports a carrier including a pair of carrier discs 23 and 24 mounted upon opposite ends of the shaft 22. The periphery of each carrier disc 23 and 24 is provided with one or more guideways 25 opening through the peripheral edge of the discs and disposed radially thereof. The radial guideways 25 in the opposed carrier discs 23 and 24 are axially aligned to support, for radial movement, a roller shaft 27. Each roller shaft 27 is generally cylindrical throughout its length, but its opposite ends 28 have square or rectangular cross-sections adapted to be slidably received in the guideways 25 of corresponding widths in the opposite discs 23, 24.

Rotatably supported on each shaft 27, by means such as ball-bearings 29 (FIG. 3) is a planetary crusher roller 30. Each roller 30 is adapted to freely rotate about its corresponding shaft 27 independently of the rotary movement of the carrier discs 23 and 24. Moreover, each crusher roller 30 is adapted to freely reciprocate radially of the corresponding carrier discs 23 and 24 in the corresponding guideways 25.

In the preferred form of the invention, each roller 30 has a diameter substantially less than the diameter of the carrier discs 23 and 24, and the periphery of the discs 23 and 24 are spaced from the inner surface of the grate 15 a radial distance less than the radius of each roller 30. In this manner, when the centrifugal motion of the discs 23 and 24 urges each roller 30 to its outer radial limit, the shaft ends 28 will still be received in their corresponding guideways 25.

The carrier shaft 22 may be driven in any convenient manner, such as by the driven pulley 32 and belt 33 from a drive pulley and motor means, not shown. The angular velocity of the carrier shaft 22 must be sulficient to produce adequate centrifugal force not only to thrust all the crusher rollers 30 radially outwardly, but also to cause the rollers 30 to exert sufficient pressure upon the material to comminute it against the cylindrical grate 15.

The length of the chute 19, that is, its dimension parallel to the axis of the carrier shaft 22, is less than the length of the rollers 30 so that each roller 30 may be supported on the inner surface of the grate 15 as it rolls past the opening 18 and to prevent the roller 30 from entering the chute 19.

In the operation of the mill, the motor means is started to drive the carrier shaft 22 through the transmission 33 and driven pulley 32 in order to rotate the carrier discs 23 and 24 within the crushing chamber 17 at the desired speed. As the carrier discs 23 and 24 rotate, the planetary crusher rollers 30 will move radially outwardly until they rollably engage the interior surface of the grate 15, by virtue of centrifugal force.

The material to be comminuted is then introduced through the feed chute 19. Some of the material will encounter a roller 30 as it moves across the bottom of the chute 19 and may be carried and rotated between the surface of the roller 30 and the inner surface of the grate 15 to be crushed. Other material introduced into the crushing chamber 17 may drop to the bottom of the grate 15 before it is encountered by any of the rollers 30. However, because of the grate 15 having slots 16 throughout its length and circumference, the position where the material is encountered by the crusher roller 30 is immaterial since the material may be comminuted and discharged at practically any position on the grate 15.

After the material is comminuted and discharged through the slots 16, the comminuted material will descend by gravity through the open bottom 12 of the housing to any desired discharge area, such as upon the conveyor belt 13 for removal from the discharge site.

The angular position of each elongated slot 16 is extremely important to the successful operation of the invention. If theelongated slots 16 were disposed parallel to the rotary axis of the shaft 22, the pressure exerted by the roller 30 upon material to be comminuted, such as aggregate or rock, will be distributed along the axially disposed edges of the slot or slots 16. Since the edges of each slot act as cutting blades or knives against which the aggregate is forced by each roller 30, then it will be understood how important the slot edges and their relative positions are. When each slot 16 is disposed at an acute angle to any radial plane intersecting the slot, as disclosed in the drawings, then the pressure exerted upon a roller 30 upon a given material particle, such as a rock, will engage only those portions of the edges of the angular slot 16 which cross the tangential surface of the roller 30. Consequently, the pressure exerted by the roller 30 is concentrated upon only the crossing portions of the slot edges, and not distributed along the full length of the slot 16.

Another advantage in employing the slot 16 at an acute angle to the radial or axial plane of the grate is that the width of each lot 16 may be smaller than the width of an axially extending slot for a given size of comminuted material. For example, the circumferential distance between the edges of a slot disposed at an angle is greater than the transverse width of the slot. Since the rollers are moving the aggregate in a circumferential direction, then it is the circumferential distance between the slot edges which is the effective width, and therefore the determining factor in the sizing of the comminuted material. However, as the angle of the slot 16 approaches zero with the radial plane, then the circumferential distance between opposite edges of a slot approaches the length of the slot. Consequently, the slots would then be disposed circumferentially of the grate 15 and would not be as effective because the function of the diagonal shearing edges is lost.

The disposition of the slots 16 at angles to the radial plane of the grate 15 also provides a shearing action as the axially disposed roller 30 proceeds circumferentially about the inner periphery of the grate 15.

For the above reasons, it is apparent that a grate 15 having the angularly disposed elongated slots 16 provides more effective cutting action in combination with the crushing rollers 30. Moreover, not as much pressure is required by each roller 30 in combination with the angular slots 16 as with axial slots, to comminute the material. Therefore, a more efficient comminuting operation is obtained.

The elongated slots 16 are preferably disposed in the axially spaced sets or annular bands separated axially from each other, so that any material which might slide along a slot in advance of the roller 30 may not slide too far before it is cut and crushed at the trailing end of the slot. Moreover, the herringbone arrangement is desired in order to alternately reverse the angular direction of the axial series of slots in order to afford maximum shearing exposure to the material regardless of its shape or orientation.

What is claimed is:

1. A centrifugal roller mill comprising:

(a) a housing,

(b) a cylindrical grate mounted in said housing so that the cylindrical axis of said grate is horizontal,

(c) said grate comprising a plurality of circumferentially spaced, elongated slots therethrough of predetermined size, each slot forming an acute angle With any radial plane intersecting said slot,

(d) a feed opening in the top portion of said grate to introduce material to be comminuted into said grate,

(e) a roller carrier having a cross-section smaller than said grate,

(f) means rotatably mounting said carrier coaxially within said grate,

(g) at least one planetary crusher roller,

(h) means mounting said roller on said carrier for free rotary movement and for radial reciprocable movement toward and away from engagement with said grate, and

(i) means for driving said carrier to rotate at sufficient velocity to urge said roller toward the elongated, angular slots in said grate.

2. The invention according to claim 1 in which said elongated slots are arranged in a herringbone pattern and said slots are of uniform width.

3. The invention according to claim 2 in which the length of each slot is substantially less than the length of said crusher roller and said slots are arranged in axially spaced, annular series of slots.

References Cited UNITED STATES PATENTS 173,411 2/1876 Lucup 241-131 799,990 9/1905 Knapp 241109 X 801,572 10/1905 Davis 24148 1,724,441 8/1929 Weir 241- 2,764,951 10/1956 Fisher 241109 X 2,797,718 7/1957 Dawkings 241-123 X FOREIGN PATENTS 1,112,739 11/1955 France.

ROBERT C. RIORDON, Primary Examiner D. G. KELLY, Assistant Examiner 

